Budgeting is the head of Managerial accounting as it's prime responsibility lies with the management. IAS deals with External Accounting not internal one.

Cash budgeting is a form of budgetary control through which we manage cash inflows and outflows. Inflows might be sales, service revenue, subscription fees and others (you might have studied revenue models) and outflows ,might be Expenses, repayment of liabilities. a model of cash budget might be:

Cash at the start of month......... xxx
Add: inflows
- Sales .................................. xxx
-service fee etc ..................... xxx
Less: Outflows
-Expenses................................(xx)
- loan repayment.......................(xx)
Cash at month end ......................... xxxx.

For detailed study consult any B.Com book of cost accounting.